Spread hazelnuts in an even layer on a baking sheet. Cook at 350 for 10 minutes or until light brown.
Remove from heat; transfer to a small bowl.
Pour boiling water over hazelnuts; cover and let stand 20 minutes. Strain hazelnut mixture through a sieve into a bowl, reserving liquid and nuts.
Spread nuts in an even layer on a double thickness of paper towels; pat lightly with additional paper towels to dry. Set aside.
Place reserved liquid in a small saucepan; heat until warm (100 to 104).
Transfer reserved liquid to a large bowl.
Add sugar and yeast, stirring well with a whisk; let stand for 5 minutes.
Lightly spoon flour into dry measuring cups; level with a knife.
Add 2 3/4 cups flour and salt; stir until a soft dough forms. Turn dough out onto a floured surface. Knead until smooth and elastic (about 8 minutes); add enough of remaining flour, 1 tablespoon at a time, to prevent dough from sticking to hands (dough will feel tacky). Cover dough; let rest 10 minutes. Uncover; knead in reserved hazelnuts.
Place dough in a large bowl coated with cooking spray, turning to coat top. Cover and let rise in a warm place (85), free from drafts, 1 hour or until doubled in size. (Press two fingers into dough. If indentation remains, dough has risen enough.) Punch dough down; cover and let rest 5 minutes. Shape dough into a 9-inch oval; place on a baking sheet sprinkled with cornmeal. Lightly spray surface of dough with cooking spray; cover.
Let rise in a warm place (85), free from drafts, 30 minutes or until doubled in size.
Preheat oven to 37
Bake at 375 for 30 minutes or until browned on bottom and sounds hollow when tapped. Cool on wire rack.
